Edward 'Ed' Knudsen, who served with the U.S. Marine Corps during two combat deployment missions in Afghanistan in support of Operation Enduring Freedom, is Rapid City's Veteran of the Month for March.

Edward 'Ed' Knudsen, who served with the U.S. Marine Corps during two combat deployment missions in Afghanistan in support of Operation Enduring Freedom, is Rapid City's Veteran of the Month for March.

Sudden cardiac arrest and heart attacks are often confused with one. But Dr. Kelly Airey, a cardiologist and cardiac electrophysiologist at Rapid City Regional Hospital, says they’re completely different in their survival rates.

Heart attacks occur when blood flow to the heart is blocked. People will have often have chest pain or experience other signs of discomfort, such as nausea or cold sweat.

Cardiac arrest is triggered by an electrical malfunction, causing an irregular heartbeat and often showing no signs before it occurs.

According to the American Heart Association, 790,000 people in the United States have heart attacks each year. Of those, 114,000 will die. However, sudden cardiac arrest has a much higher death toll. Around 350,000 people will suffer from cardiac arrest, with 90 percent of cases fatal.

Airey says there is very little time to react to someone who is suffering from cardiac arrest, which is why the survival rate is so low.

“The number is just very, very small,” she says. “And the reason that is, is because people don’t get immediate defibrillation. And when they don’t get immediate defibrillation, then the outcomes are very, very poor.”

Although no demographic is completely safe from either sudden cardiac arrest or heart attacks, the chances increase as people age.

“In the post-menopausal female population, we see more heart attacks,” Airey says. “In fact, this kind of death is the number one cause of death in women … heart disease and stroke, which eventually can lead to sudden cardiac death. And then also in men - usually starting in the age group of about 45 or so - that’s when we see cardiac death.”

Exercise is beneficial for heart health and aids in prevention of many other cardiac conditions, but there is a limit on just how strenuous exercise should be. Airey says people who endure strenuous exercise are more prone to be a cardiac arrest victim.

“The number one cause of sudden cardiac death over 35 years of age, is from really, really strenuous exercise, especially cycling,” Airey says. “So that’s one of the things we get concerned about in older people who really push themselves with exercise - particularly when they’re not prepared for it.”

In fact, there’s a formula for the level of strenuous exercise that a person should endure. Your maximum heart rate is 220, minus your age, multiplied by .85. For example, someone who’s 40 years old should have a target heart rate of 153 beats per minute.

Airey also says that everyone should know basic CPR, as well as how to use a defibrillator in case of an emergency.